Designed for the HT1 arrow, we have developed the Arrow Protection System (APS) that features unbeatable strength and penetration. The APS outsert is made of 7075 aircraft grade aluminum and encapsulates the end of the shaft so that the aluminum is absorbing the shock rather than the carbon shaft. These are also sized according to your particular spine, making for a tighter fit and smoother transition to the shaft. The overall outsert is 1 3/8" long with 5/8" of that covering the end of the shaft.